The present invention relates to an extremely thin grinding wheel coated with super abrasive grains such as diamond grains and cubic system boron nitride, and to a process for producing the same.
Heretofore, grinding of flat surfaces of a hard, brittle workpiece (1) like silicon and glass has been accomplished by the use of a ring grindstone (2) attached to the open end of an inverted revolving cup (3) as shown in FIG. 1. The use of such conventional grindstone (2) involves many problems. The side and bottom of the grindstone crossing at right angles provides a large area in contact with the workpiece (1), thereby generating a large amount of friction heat and impairing the dimensional accuracy of the work due to thermal expansion. Moreover, loading of pores with chips is likely to occur, resulting in dulling, burn marks, and grinding cracks. In addition, the cutting edge of the grindstone (2) becomes dull during grinding, causing the grindstone to escape from the work. This makes it difficult to grind the work with one pass, and makes it necessary to repeat the grinding bit by bit in order to grind the work to a desired thickness. This is very inefficient. In another type of conventional grindstone, the bottom is tapered inwardly as shown in FIG. 2. This grindstone still has a large contact area and is easy to lose sharpness, masking it necessary to regenerate the taper.